The performance of a variety of monitoring systems may be affected by where a sensor or its parts are placed relative to a target (e.g., a human such as an adult, teen, child, or baby) that is being monitored. For example, certain monitoring systems may require a sensor to be in physical contact with a target and may further require a part (e.g., a power or data cable) to be connected from a sensor to a monitoring device. Installing sensor parts in, for example, a baby crib may be contrary to expert advice to keep the baby crib free of such objects (e.g., based on the sensor parts constituting a strangulation or suffocation hazard). Alternatively, the sensor may require wireless communication between a sensor and a monitoring device, thereby introducing potentially harmful or interfering communication waves (e.g., radio frequency waves, microwave communication waves, etc.) in close proximity to the baby, another target of the monitoring system, or other electronic equipment.
Known monitoring systems require a sensor to be directly in contact with a target. For example, a traditional electrocardiogram (ECG) uses external electrodes to detect a patient's ECG signal. The external electrodes are located on the ends of cables and must be physically placed on a patient and near the patient's heart. This often necessitates the use of conductive materials that may be inconvenient to hook up and use, especially for long-term monitoring of a relatively active patient. These devices have significant limitations. For example, the patient must be physically connected to the device. If the patient wants to leave his or her bed, the device needs to be detached from, and then re-attached to the patient on his/her return, often by a highly trained staff member. The inconvenience and the delays associated with setting up such monitoring systems mean that they are not well-adapted to long-term use and, as a result, may miss detecting important but transient episodic events. These monitoring systems are also not well-suited for monitoring more active targets, for example, a baby in a crib or a person exercising on a piece of exercise equipment. Although there are monitoring systems incorporated into devices such as wristbands and armbands that are more suited to an active lifestyle, they still typically need to be directly in contact with the target, and generally provide limited information and functionality.
Accordingly, there is a need for a monitoring system that does not require a sensor to be directly in contact with a target. There is also a need for a monitoring system that can assist in the management of a target's health, fitness, sleep and diet by monitoring changes in a person's body. There is further a need for a monitoring system suitable for long-term use that can sense changes in a target and provide timely and appropriate diagnostic, prognostic and prescriptive information.